Capstone Project Overview

finance_tracker/
├── __init__.py
├── models.py          # Transaction, Category classes
├── storage.py         # JSON/SQLite persistence
├── analysis.py        # Reports, summaries, charts (ASCII)
├── cli.py             # Command-line interface
└── tests/
    ├── test_models.py
    ├── test_storage.py
    └── test_analysis.py

from dataclasses import dataclass
from datetime import datetime
from decimal import Decimal
from typing import Optional
from enum import Enum

class TransactionType(Enum):
    INCOME = "income"
    EXPENSE = "expense"

@dataclass
class Category:
    name: str
    budget: Optional[Decimal] = None

@dataclass
class Transaction:
    id: int
    amount: Decimal
    type: TransactionType
    category: str
    description: str
    date: datetime
    created_at: datetime

class Storage:
    def load(self) -> list[Transaction]: ...
    def save(self, transactions: list[Transaction]): ...
    def add_transaction(self, transaction: Transaction): ...
    def delete_transaction(self, transaction_id: int): ...

class JSONStorage(Storage):
    """JSON file-based storage."""

class SQLiteStorage(Storage):
    """SQLite database storage (bonus)."""

class Analyzer:
    def balance(self) -> Decimal: ...
    def monthly_summary(self, year: int, month: int) -> dict: ...
    def category_breakdown(self) -> dict: ...
    def cash_flow(self) -> list[tuple[str, Decimal]]: ...

class CLI:
    def add_transaction(self, args): ...
    def list_transactions(self, args): ...
    def show_balance(self): ...
    def monthly_report(self, args): ...
    def export(self, args): ...